This application is directed to lubricant compositions containing small additive concentrations of mixed hydroxyaryl-hydroxyester borates having excellent multifuntional/antioxidant activity.
The use of hydroxyaryls have been well known for their antioxidant properties in a variety of petroleum and non-petroleum products. The use of borates have found extensive application in such diverse areas as grease additives, brake and hydraulic fluids, and fuel and combustion additives. The use of hydroxyesters have been widely reported as having beneficial multifunctional characteristics in a variety of fuel and lubricant applications.
U.S. Pat. Nos. 4,655,948 and 4,781,850 relate to grease compositions containing borated catechol (ortho-dihydroxybenzene, e.g., catechol-alcohol borates useful in reducing dropping point.
U.S. Pat. Nos. 4,594,171 and 4,568,472 discloses the use of borated additive compounds such as borated hydroxyesters in lubricant compositions. U.S. Pat. No. 4,654,082 discloses the use of hydroquinones as an antioxidant in ink compositions. U.S. Pat. No. 4,223,735 discloses the use of of hydroquinones as an oxidation inhibitor in a method of producing petroleum.
U.S. Pat. No. 4,240,970 in one embodiment is directed to the use of (1) the product of reaction between an alkenylsuccinic acid, ester or anhydride and a hydroxyaromatic (hydroxyaryl) compound and (2) the product of reaction of (1) and an amine as detergents in lubricant compositions.
Lubricant compositions containing small additive concentrations of mixed hydroquinone-hydroxyester borates such as hydroquinone-glycerol monoleate borates as disclosed in Ser. No. 078,949, possess excellent antioxidant activity.
It has now been found that the use of these novel mixed hydroxyaryl-hydroxyester borates provide exceptional antioxidant and corrosion inhibiting activity with the potential for antifatigue, friction reducing, antirust and high temperature stabilizing properties. These novel borates are also highly useful not only in oils of lubrication viscosity but also in solid lubricants such as greases.